Heating devices of this type are used for various fluid heating devices, for example, continuous liquid heating devices, continuous liquid sterilization devices, and hot water manufacturing devices.
Examples of methods for sterilizing liquid foods include the indirect heating method in which the food is heated indirectly through a metal wall and the like, and the direct vapor heating method in which the liquid is directly heated by vapor. Among these, there is a trend that as a method for sterilizing liquids which are easily burnt, such as coffee creamer and soybean milk, or liquids which are easily discolored, such as aojiru (juice of green, leafy vegetables), the direct vapor heating method which requires a shorter heating time, has small thermal effect on the liquid, and is capable of preventing degradation of the quality of the liquid is preferably used.
For example, Japanese Unexamined Patent Publication No. 2004-201533 (Patent Document 1) discloses that a vapor blowing direct heat sterilizer comprising an injection heater in which the liquid is heated to a sterilization temperature by blowing vapor directly into the liquid to be sterilized.
Japanese Unexamined Patent Publication No. 2000-300976(Patent Document 2) discloses a continuous fluid heating device which consists of a metering pump for transferring a fluid to be heated, and a static mixer which heats the fluid to be heated transferred from the metering pump by directly mixing steam into the fluid.
Patent Document 2 describes that a dispersive mixer disclosed in Japanese Utility Model Publication No. 1995-37703(Patent Document 3) can be used as the static mixer by which vapor (steam) is blown and mixed directly into the fluid to be heated. In this document, the dispersive mixer disclosed in Patent Document 3 mainly comprises, thereinside, a conduit pipe for passing a main fluid (fluid to be heated) on which a stirring element such as a twisted plate is fixed, a nozzle connected to the inside of this conduit pipe, and a header for infusing an infusion fluid (vapor) into the conduit pipe via this nozzle, and a force-feed means for force-feeding the infusion fluid to the header.